When it comes to most basic DIY projects—interior painting and replacing carpeting—I was surprised to learn how often folks wade in, carefully plotting color and pattern schemes with little or no attention paid to the type of light or lighting that will illuminate the 'finished product.'

Paint squares of primed drywall with samples of the colors you're considering, and then move them around the room during the day. Apply at least two coats.

Evaluate samples of carpet during different daylight conditions.

Most contractors won't hang lights before you paint, but you can get a color approximation by placing a bulb you'll be using in a floor or desk lamp.

Natural and artificial light will work together during certain times of day, especially in summer when dusk lasts a long time. So turn on artificial lights even during daylight to see what your colors will look like.

Glossy finishes will reflect light and change the way the color looks, whereas flat finishes are less reflective and allow colors to look truer under bright light.

Light-colored walls can reflect the colors of bold carpets: A bright blue rug, for instance, can cast a bluish tone on a white wall.

Homeowners also need to take into account how sunlight affects colors. Cole reminds remodelers that as the amount and angle of the sun changes, so will your colors.

Light in north-facing rooms is cool and bluish. So bolder colors show up better than muted colors; and lighter colors will look subdued, says Cole.

Lots of high-in-the-sky light in south-facing rooms brings out the best in cool and warm colors. Dark colors will look brighter; and lighter colors will virtually glow.

East light is warm and yellowy before noon, then turns bluer later in the day, Cole says. These are great rooms for reds, oranges and yellows.

While evening light in west-facing rooms is beautiful and warm, while scant morning light can produce shadows and make colors look dull.